Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a view of a display screen or portion thereof with atransitional graphical user interface showing a first image in asequence of a first embodiment according to the claimed design;

FIG. 2 is a second image in the sequence thereof;

FIG. 3 is a third image in the sequence thereof;

FIG. 4 is a view of a display screen or portion thereof with atransitional graphical user interface showing a first image in asequence of a second embodiment according to the claimed design;

FIG. 5 is a second image in the sequence thereof; and,

FIG. 6 is a third image in the sequence thereof.

The appearance of the transition is sequential from FIG. 1 through FIG.3 in the first embodiment and from FIG. 4 through FIG. 6 in the secondembodiment. The process or period in which an image transitions toanother image forms no part of the claimed design.

The shading or level of intensity of lines shown in the images are partof the claimed design.

The longer-incremented broken-lines illustrate an electronic device, andthe intermediate-length broken-lines illustrate a boundary of a displayscreen or portion thereof. The remaining broken lines illustrateportions of the graphical user interface. None of the broken lines formpart of the claimed design.

CLAIM The ornamental design for a display screen or portion thereof witha transitional graphical user interface, as shown and described.